Light measuring device

Abstract

To provide an optical measuring device improved in light use efficiency.SOLUTION: A conveyance device 400 supports and conveys an object OBJ. The conveyance device 400 has a support portion 401 with an opening 402 smaller than the object OBJ provided at a position where the object OBJ is supported. A lighting device 200 emits measurement light SIN which chronologically varies in wavelength, to a first surface of the object OBJ, through the opening 402 of the support portion 401. A light receiving device 300 detects object light SOBJ which is diffused transmission light emitted from a second surface of the object OBJ.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an optical measurement device.

Background Art

[0002] Spectral analysis is widely used for component analysis and inspection of objects. In spectral analysis, measurement light is irradiated onto an object, and the spectrum of the object light obtained as a result of the irradiation is measured. Then, based on the relationship between the spectrum of the object light and the spectrum of the measurement light, optical properties such as reflection characteristics (wavelength dependence) or transmission characteristics can be obtained.

[0003] Spectral analysis is classified into a transmission type that uses transmitted light of an object as object light and a reflection type that uses reflected light as object light. The reflection type is suitable for measuring objects with high reflectivity, but the optical information obtained is limited to that near the surface of the object. Therefore, in measurements of precision industrial products, specimens collected from animals and plants, substances ingested by humans into the body, liquids and gases produced in production plants, etc. as objects, sufficient accuracy cannot be achieved.

[0004] The transmission type is suitable for cases where the object is food or beverages (hereinafter collectively referred to as food and drinks) because it can obtain optical properties including not only the surface but also deep parts of the object. Patent Documents 1 and 2 disclose transmission type product inspection devices. This product inspection device includes an irradiation optical system that irradiates pulsed light onto the surface of a product (object to be inspected) and a light receiver that is provided on the back side of the product and receives the light transmitted through the product.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] As a result of studying a transmission type inspection apparatus, the inventor has come to recognize the following problems. FIG. 1 is a diagram showing a transmission type inspection apparatus 1000 studied by the inventor. Note that this inspection apparatus 1000 should not be recognized as a known technique.

[0007] The product P is supported and conveyed by a support means 1400.

[0008] As shown in Patent Documents 1 and 2, the illumination device 1200 irradiates the upper surface of the product P with pulsed light (measurement light S IN ). The light receiver 1300 is provided below the product P and receives the object light S OBJ radiated from the bottom surface side of the product P. This object light S OBJ has diffused transmitted light as a main component and is radiated from the entire bottom surface of the product P.

[0009] Since it is costly to configure the support means 1400 with a material transparent to the object light S OBJ , an opaque support means 1400 may be used for the object light S OBJ . In this case, an opening 1102 for extracting the object light S OBJ is required directly below the product P of the support means 1400. If the opening 1102 is too large, the product P will fall, so the size (width) of the opening 1102 needs to be narrower than that of the product P.

[0010] Only the object light S OBJ that has passed through the opening 1102 can enter the light receiver 1300, and a part of the object light S OBJ of the product P is blocked by the support means 1400. The narrower the width of the opening 1102, the smaller the amount (intensity) of the object light S OBJ entering the light receiver 1300, leading to a decrease in measurement accuracy.

[0011] In order to increase the amount of the object light S OBJ entering the light receiver 1300, the intensity of the measurement light S IN may be increased. However, depending on the type of the product P, a strong measurement light SIN Since the irradiation of has problems such as causing the product P to deteriorate, the measurement light S that can be irradiated IN has an upper limit I MAX in intensity in some cases. When the transmittance of the product P is α and the shielding rate (transmittance) of the support means 1400 is β, the maximum incident intensity I DET(MAX) on the light receiver 1300 is I DET(MAX) = I MAX × α × β and the amount of light received is reduced by the support means 1400. The reduction in the amount of light received leads to a decrease in measurement accuracy.

[0012] When a material such as glass is used as the support means 1400, the opening 1102 may become unnecessary, but even in this case, it is impossible for the transmittance β to be 100%. Therefore, the maximum incident intensity I DET on the light receiver 1300 is DET = I MAX × α × β, and the amount of light received is reduced by the support means 1400. The reduction in the amount of light received leads to a decrease in measurement accuracy.

[0013] The present disclosure has been made in view of such problems, and an exemplary object of one of its aspects is to provide an optical measurement device with improved measurement accuracy.

Means for Solving the Problems

[0014] One aspect of the present disclosure relates to an optical measurement device. The optical measurement device includes a transport device that supports and transports an object, the transport device supporting the object at its support portion, an illumination device that irradiates the first surface of the object with measurement light whose wavelength changes over time through the support portion, and a light receiving device that detects diffused transmitted light radiated from the second surface of the object.

[0015] In addition, combinations of the above components arbitrarily, and those obtained by mutually substituting the components and expressions of the present disclosure among methods, devices, systems, etc. are also effective as aspects of the present disclosure.

Advantages of the Invention

[0016] According to an aspect of the present disclosure, the measurement accuracy can be improved.

Brief Description of the Drawings

[0017]

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Figure 13

Modes for Carrying Out the Invention

[0018] (Overview of the Embodiment) An overview of some exemplary embodiments of the present disclosure will be described. This overview is for the purpose of providing a basic understanding of the embodiments as a prelude to the detailed description that follows, and simplifies and describes some concepts of one or more embodiments. It does not limit the scope of the invention or the disclosure. Also, this overview is not an all-inclusive overview of all possible embodiments and does not limit essential components of the embodiments. For convenience, "one embodiment" may be used to refer to one embodiment (example or variation) or a plurality of embodiments (examples or variations) disclosed herein.

[0019] An optical measurement device according to one embodiment includes a transport device that supports and transports an object, the transport device supporting the object at its support portion, an illumination device that irradiates the first surface of the object with measurement light whose wavelength changes over time through the support portion, and a light receiving device that detects diffused transmitted light radiated from the second surface of the object.

[0020] According to this configuration, more diffused transmitted light radiated from the object can be detected by the light receiving device without being blocked by the support portion, so the measurement accuracy can be improved. Note that "support" includes not only fixing the object but also holding it within a certain range.

[0021] In one embodiment, the support portion may be provided with an opening narrower than the object. The illumination device may irradiate the first surface of the object with the measurement light through the opening of the support portion.

[0022] In one embodiment, the transport device has a plurality of support portions each of which supports the object, and the plurality of support portions may each include a recess provided on a common surface of the transport device. The opening may be a through hole formed in the bottom surface of the recess.

[0023] In one embodiment, the illumination device includes a folding mirror provided below the transport device, and the folding mirror may reflect measurement light incident from the side surface of the transport device toward the first surface of the object.

[0024] In one embodiment, without using a folding mirror, the lighting device may be provided below the transport device.

[0025] In one embodiment, the light receiving device may include a light sensor smaller in size (outer dimensions) than the object and a condensing optical system including a lens larger in size (outer dimensions) than the object. The inventors have recognized that when a specific object is to be inspected, the diffused transmitted light, which is object light, has low directivity and is radiated over a wide range. In this case, by using a lens larger than the object, as much diffused transmitted light as possible can be condensed onto the light sensor.

[0026] In one embodiment, the light receiving device may include a light sensor and may be configured such that a component of the diffused transmitted light of the object radiated in a direction deviated from the optical axis of the measurement light enters the light sensor. Note that "configured" includes not only cases where the configuration is characteristic, but also cases where both the configuration and the arrangement are characteristic, or cases where only the arrangement is characteristic. According to this optical measurement device, when an object is present, the object light attenuated by the object enters the light sensor. When the object is not present, no measurement light enters the light sensor, or even if it enters, the intensity is extremely weak, so the light sensor can be protected. In addition, regardless of the presence or absence of the object, the lighting device can be continuously operated, and a shutter or the like synchronized with the presence or absence of the object is not required.

[0027] In one embodiment, the wavelength of the measurement light may change over time. In one embodiment, the measurement light may be pulsed light whose wavelength changes over time within one pulse.

[0028] (Embodiment) Hereinafter, the present disclosure will be described with reference to the drawings based on preferred embodiments. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. Further, the embodiments are illustrative rather than limiting the disclosure, and not all features or combinations thereof described in the embodiments are necessarily essential to the disclosure.

[0029] The dimensions (thickness, length, width, etc.) of each member described in the drawings may be enlarged or reduced as appropriate for ease of understanding. Furthermore, the dimensions of a plurality of members do not necessarily represent their size relationships. On the drawing, even if a member A is drawn thicker than another member B, member A may be thinner than member B.

[0030] FIG. 2 is a block diagram of an optical measurement device 100 according to an embodiment. The optical measurement device 100 is a spectrometer that measures the transmission spectrum of an object OBJ, and mainly includes an illumination device 200, a light receiving device 300, a transport device 400, and a processing device 500. In some figures, the illumination device 200, the light receiving device 300, etc. may be shown simply as boxes, but this is not intended to mean that the members constituting each are housed in a single housing.

[0031] The transport device 400 transports the object OBJ so as to cross the irradiation region 10.

[0032] The transport device 400 has a support portion 401 and supports the object OBJ at the support portion 401. An opening 402 narrower than the object OBJ is provided at the location where the object OBJ is supported on the support portion 401, and the support portion 401 supports the object OBJ in a manner that the object OBJ straddles the opening 402. The width of the opening 402 is determined so that the object OBJ does not fall from the opening 402. Therefore, the width of the opening 402 may be narrower than the length in the width direction of the object OBJ.

[0033] The illumination device 200 emits measurement light S whose wavelength changes over time to the first surface (bottom surface) of the object OBJ present in the irradiation region 10IN is irradiated from below the support portion 401 through the opening 402. The measurement light S IN In order to suppress the measurement light S from being blocked by the support portion 401, IN the beam diameter of is condensed to be smaller than the opening 402.

[0034] The measurement light S IN has a one-to-one correspondence between time and wavelength. This is what the measurement light S IN is said to "have wavelength uniqueness". The illumination device 200 may be configured using known techniques, for example, those described in Patent Documents 1 and 2 can be used.

[0035] FIG. 3 is a diagram showing the measurement light S IN In the upper part of FIG. 3, the intensity (time waveform) I IN (t) of the measurement light S, and in the lower part shows the temporal change of the wavelength λ of the measurement light S IN (t). IN

[0036] In this example, the measurement light S IN is one pulse, the main wavelength is λ1 at the leading edge thereof, the main wavelength is λ2 at the trailing edge, and the wavelength changes over time between λ1 and λ2 within one pulse. In this example, the measurement light S IN is a positive chirp pulse (λ1 > λ2) whose frequency increases with time, in other words, whose wavelength becomes shorter with time. Note that the measurement light S IN may be a negative chirp pulse whose wavelength becomes longer with time (λ1 < λ2).

[0037] Returning to FIG. 2. The measurement light S IN is irradiated to the bottom surface side of the object OBJ, passes through the object OBJ, and is radiated as transmitted light (hereinafter also referred to as object light) S OBJ from the second surface (upper surface) thereof. When the spectrum of the measurement light S IN is I IN (λ) and the wavelength dependence of the transmittance of the object light S OBJ is T(λ), the spectrum I OBJ (λ) of the object light S OBJ is represented by an equation. ​I OBJ I(λ)=T(λ)×I IN (λ) …(1)

[0038] Object light S OBJ The object light S may include direct transmitted light and diffused transmitted light. However, this embodiment is particularly suitable for spectral measurement of an object OBJ in which diffused transmitted light is dominant. The direct transmitted light is radiated in the same direction as the optical axis OA2 of the measurement light S IN whereas the object light S which is diffused transmitted light OBJ is radiated not only in the direction of the optical axis OA2 of the measurement light S IN but also widely in different directions. For example, the diffused transmitted light is radiated with an intensity distribution having a cosine characteristic when the direction of the optical axis OA2 is set to 0°.

[0039] The light receiving device 300 is provided on the side opposite to the lighting device 200 with the support portion 401 interposed therebetween, in other words, above the support portion 401, and detects the diffused transmitted light radiated from the upper surface of the object OBJ. The light receiving device 300 includes a photosensor 302 that detects the diffused transmitted light of the object OBJ as the object light S OBJ The light receiving device 300 may include a condensing optical system etc. in addition to the photosensor 302 as will be described later, but is omitted in FIG. 2.

[0040] The photosensor 302 is a photoelectric conversion element that converts an optical signal into an electrical signal, and examples thereof include a photodiode, an avalanche photodiode, a phototransistor, a photomultiplier tube (photomultiplier) that utilizes the photoelectric effect, and a photoconductive element that utilizes a change in electrical resistance due to light irradiation.

[0041] The output of the photosensor 302 is converted into a digital detection signal by an A / D converter and supplied to the processing device 500. The detection signal indicates the time waveform I OBJ (t) of the object light S OBJ (t).

[0042] Based on the output signal of the light receiving device 300, the processing device 500 generates the spectrum I OBJ (λ) of the object light S OBJ (λ). Then, the measurement light S INSpectrum I IN (λ) and object light S OBJ Spectrum I OBJ Based on (λ), the transmittance T(λ) of the object OBJ is calculated. T(λ) = I OBJ (λ) / I IN (λ) …(2)

[0043] On the side of the illumination device 200 with respect to the object OBJ, a part of the measurement light S IN is branched into a separate path using a beam splitter or the like, and the time waveform I IN of the branched measurement light S IN (t) is measured with a light receiving device (not shown in FIG. 2) different from the light receiving device 300, and the spectrum I IN of the measurement light S IN (λ) may be obtained. Alternatively, when the stability of the measurement light S IN is high, the previously measured spectrum I IN (λ) can be held and used.

[0044] FIG. 4 is a diagram for explaining the spectroscopy by the optical measurement device 100 of FIG. 2. As described above, since the measurement light S IN has a one-to-one correspondence between the time t and the wavelength λ, the waveform I IN (t) in the time domain can be converted into the spectrum I IN (λ) in the frequency domain.

[0045] The time waveform I IN of the object light S OBJ generated from this measurement light S OBJ (t) also has a one-to-one correspondence between the time t and the wavelength λ. Therefore, the processing device 500 can convert the waveform I OBJ of the object light S indicated by the output of the light receiving device 300 OBJ (t) into the spectrum I OBJ of the object light S OBJ (λ).

[0046] The processing device 500 calculates the ratio I OBJ (λ) and I IN (λ) of the two spectra I OBJ(λ) / I IN Based on (λ), the transmission spectrum T(λ) of the object OBJ can be calculated.

[0047] Measurement light S IN Assume that the relationship between the wavelength λ and the time t in is represented by a function λ = f(t). Most simply, the wavelength λ changes linearly with respect to the time t according to a linear function. Object light S OBJ The time waveform I OBJ (t) decreases at a certain time t x , the transmission spectrum T(λ) means that it has an absorption spectrum at the wavelength λ x = f(t x ).

[0048] Note that the processing in the processing device 500 is not limited to this. The ratio T(t) = I of the two time waveforms I OBJ (t) and I IN (t) is calculated, and after that, the transmission spectrum T(λ) may be calculated by converting the variable t of this time waveform T(t) to λ. OBJ (t) / I IN (t).

[0049] The above is the configuration of the optical measurement device 100. According to this optical measurement device 100, the object OBJ is irradiated with the measurement light S IN from the support part 401 side, and the diffused transmitted light radiated from the surface of the object OBJ on the side opposite to the support part 401 is detected as the object light S OBJ . As a result, since the object light S OBJ is not blocked by the support part 401, the light receiving device 300 can capture more object light S OBJ , and the light utilization efficiency can be improved.

[0050] Subsequently, a specific embodiment of the optical measurement device 100 will be described.

[0051] (Embodiment 1) FIG. 5 is a diagram showing the optical measurement device 100A according to Embodiment 1. The transport device 400 has a plurality of support portions 401, and each support portion 401 is configured to be able to support (fix) the object OBJ. Below FIG. 5, a cross-sectional view of the support portion 401 is shown. The support portion 401 has a recess 410 into which the object OBJ fits. This recess 410 is formed on a common surface 406 and has a diameter larger than that of the object OBJ. Further, a through-hole 412 having a diameter smaller than that of the object OBJ is formed on the bottom surface of the recess 410. This through-hole 412 corresponds to the above-described opening 402. The object OBJ is placed so as to straddle the through-hole 412. Further, through this through-hole 412, measurement light S IN is irradiated to the bottom surface side of the object OBJ. The light receiving device 300 is provided above the irradiation region 10 so as to face the upper surface of the object OBJ.

[0052] The transport device 400 further includes a suction box 430. The inside of the suction box 430 is maintained at a negative pressure by a pump (not shown) for exhaust, the through-hole 412 serves as an intake port, and the object OBJ is sucked to the through-hole 412. With this configuration, it is possible to prevent the object OBJ from falling off the recess 410.

[0053] The lighting device 200 includes a folding mirror 202. The folding mirror 202 is provided inside the transport device 400, more specifically, inside the suction box 430, directly below the through-hole 412 which is the opening 402. Outside the suction box 430, a light source head 204 that generates the measurement light S IN is provided, and a window 432 through which the measurement light S IN passes is provided on the side surface of the suction box 430. Through this window 432, the measurement light S IN enters the folding mirror 202 from the side surface of the transport device 400. The folding mirror 202 reflects the measurement light S IN toward the object OBJ. Since the window 434 only needs to allow the measurement light S IN to pass through, its size can be made small, and the influence on the pressure inside the suction box 430 is sufficiently small. The window 434 allows the measurement light S INIt may be glass that is transparent to the wavelength band, and in this case, the influence on the pressure of the window 434 can be eliminated.

[0054] (Example 2) FIG. 6 is a diagram showing the optical measurement device 100B according to Example 2.

[0055] In Example 2, the measurement light S IN is irradiated directly onto the bottom surface of the object OBJ from below the transport device 400 without using a folding mirror. For example, a window 434 is provided on the bottom surface of the suction box 430, and the measurement light S IN can pass through the window 434 and the through hole 412 and be irradiated onto the bottom surface of the object OBJ.

[0056] In Example 2, since a folding mirror is not required compared to Example 1, the configuration can be simplified.

[0057] In Example 1 and Example 2, when the object OBJ is not sucked, the suction box 430 can be omitted.

[0058] (Example 3) FIG. 7 is a diagram showing the optical measurement device 100C according to Example 3. In Example 3, the object OBJ is supported against gravity in the recess 410 by using vacuum suction by the suction box 430. The light receiving device 300 is disposed below the transport device 400. Note that, similar to Example 1, a folding mirror is disposed inside the suction box 430, and the measurement light S IN generated by the light source head 204 may be incident on the folding mirror from the side of the suction box 430.

[0059] (Example 4) FIGS. 8(a) to (c) are diagrams showing a configuration example of the support portion 401. The transport device 400 is a movable table and includes a plurality of holders 450 formed integrally with or separable from the table 440. The plurality of holders 450 are arranged at equal intervals or unequal intervals in the transport direction.

[0060] FIG. 8(b) shows a cross-sectional view of the support portion 401. The holder 450 is formed with a depression 452 having a diameter slightly larger than that of the object OBJ and an opening 454 having a diameter smaller than that of the object OBJ. The object OBJ is supported and conveyed while being housed in the depression 452 of the holder 450.

[0061] The table 440 is formed with an opening 442 so as to overlap with the opening 454. The opening 442 and the opening 454 correspond to the above-described opening 402.

[0062] The object OBJ to be inspected is mounted in the depression 452 of the holder 450 upstream (not shown).

[0063] As shown in FIG. 8(c), a depression 456 may be formed so as to penetrate the holder 450.

[0064] (Example 5) FIG. 9 is a diagram showing the optical measurement apparatus 100E according to Example 5. In Example 5, the transport device 400 is a roller conveyor and includes a plurality of rollers 422 provided at intervals in the transport direction. In this Example 5, the gap between two adjacent rollers 422 can be used as the above-described opening 402.

[0065] (Example 6) When the illumination device 200 can be sufficiently miniaturized, the illumination device 200 may be disposed in the suction box 430.

[0066] (Example 7) FIG. 10 is a diagram showing the optical measurement apparatus 100F according to Example 7. In the previous description, the case where the opening 402 is provided in the support portion 401 of the transport device 400 has been described, but it is not limited thereto. In Example 7, the opening 402 of the support portion 401 is omitted, and instead, the support portion 401 is made of a transparent material such as glass or resin. The illumination device 200 is measurement light S whose wavelength changes with time INis irradiated onto the first surface of the object OBJ through the transparent support portion 401. The light receiving device 300 detects the diffused transmitted light S radiated from the second surface of the object OBJ OBJ is detected.

[0067] The advantages of this optical measurement device 100F will be described. The advantages of this optical measurement device 100F will become clear by comparison with the comparative technique. FIG. 11 shows an optical measurement device 100R according to the comparative technique. In the comparative technique, the support portion 401 is made of glass or the like, and the measurement light S IN is irradiated onto the object OBJ from above, and the object light S OBJ is measured by the light receiving device 300 below the support portion 401.

[0068] Let the transmittance of the object light OBJ be α, the transmittance of the support portion 401 be β, and the maximum intensity that can be irradiated onto the object OBJ be I MAX Then, the maximum incident intensity I DET(MAX) of the light incident on the light receiving device 300R is I DET(MAX) = I MAX × α × β That is, the lower the transmittance β of the support portion 401, the smaller the maximum incident intensity I DET(MAX) becomes, and the measurement accuracy decreases.

[0069] On the other hand, in Example 7, the intensity I IN ’ of the measurement light S IN ’ after passing through the support portion 401 is I IN × β = the maximum intensity I MAX So, the intensity I IN of the light emitted from the lighting device 200 can be adjusted. I IN = I MAX / β At this time, the maximum incident intensity I DET(MAX) of the light incident on the light receiving device 300 is I DET(MAX) = I IN × β × α = I MAX × α That is, the light receiving device 300 can detect a large amount of light without being affected by attenuation and light shielding in the support portion 401, and the measurement accuracy can be improved.

[0070] (Regarding the light receiving device) When the present inventors inspect an object such as a food or drink product in which powder is solidified into a solid shape, the diffused transmitted light, which is the object light S OBJ has low directivity and is recognized to be radiated over a wide range. In the case of an object with an extremely low transmittance (for example, when fine powder is solidified hard to a thickness of about 3 mm, the transmittance becomes several percent or less, more specifically 1% or less), in order to perform high-precision spectroscopy, it is necessary to detect as much of the object light S OBJ as possible.

[0071] FIG. 12 is a diagram showing a configuration example of the light receiving device 300. The light receiving device 300 includes a photosensor 302 and a condensing optical system 310. In spectroscopy using chirped pulse light, high-speed responsiveness of the photosensor 302 is required. The responsiveness of the photosensor 302 is more advantageous as its area is smaller. Therefore, it is preferable to use a light receiving portion having the sensitivity of the photosensor 302 that is smaller than the object OBJ. For example, one having a diameter of about 0.5 to 1 mm may be used. On the other hand, in order to make the object light S OBJ diffusing over a wide range from the object OBJ enter the photosensor 302 with a small light receiving portion, a condensing optical system 310 is provided. The condensing optical system 310 can typically use one or a plurality of lenses 312.

[0072] The condensing optical system 310 is configured using a lens 312 whose diameter is sufficiently larger than the object OBJ. By using a lens 312 larger than the object OBJ, as much diffused transmitted light as possible can be condensed onto the photosensor 302.

[0073] (Applications) Next, the use of the optical measurement device 100 according to the embodiment will be described. The optical measurement device 100 can be used as an inspection device for products such as food and drink products in which powders are solidified into a solid form. FIG. 13 is a diagram showing an inspection device 800 which is one form of the optical measurement device 100. The inspection device 800 inspects a large number of products P such as food and drink products and determines whether they are good or bad. In the case of food and drink products, their transmittance is on the order of 1 / 100 to 1 / 1000.

[0074] As described with respect to the optical measurement device 100, the inspection device 800 includes an illumination device 200, a light receiving device 300, a transport device 400, and a processing device 500. Further, the inspection device 800 includes a light receiving device 810, a beam damper 820, a digitizer 830, and a pump 840.

[0075] The illumination device 200 includes a light source 210, a pulse stretcher 220, and an irradiation optical system 230. The light source 210 generates coherent pulsed light having a wide continuous spectrum in a continuous spectrum of at least 10 nm, specifically, in the near-infrared region of 900 to 1300 nm. The light source 210 may be an SC (Super Continuum) light source including a pulsed laser and a nonlinear element. As the pulsed laser, a mode-locked laser, a microchip laser, a fiber laser, or the like can be used. As the nonlinear element, a nonlinear fiber such as a photonic crystal fiber can be used.

[0076] The pulse stretcher 220 stretches the pulse width of the pulsed light generated by the light source 210 in a manner in which time and wavelength correspond one-to-one. The pulse stretcher 220 may be composed of a single wavelength dispersion fiber.

[0077] Alternatively, the pulse stretcher 220 may be composed of a wavelength division multiplexer that branches the pulsed light into a plurality of paths for each wavelength, a plurality of fibers (fiber bundles) that provide different delays for each of the plurality of paths, and a wavelength division multiplexer that recombines the outputs of the plurality of fibers. The wavelength division multiplexer can be composed of a planar lightwave circuit (PLC), and specifically, it may be composed of an array waveguide grating (AWG). The plurality of fibers that make up the fiber bundle have different lengths.

[0078] The support portion 401 of the transfer device 400 is provided with a recess 410. Inside the recess 410, a plurality of products P are placed by a mounter (not shown) upstream (the left side in the figure). The transfer device 400 moves the plurality of support portions 401 in their arrangement direction (the right direction in the figure). Note that, among the surfaces of the recess 410, the surface on which the product P is placed is referred to as the front surface, and the opposite surface is referred to as the back surface.

[0079] The irradiation optical system 230 irradiates the extended pulse as the measurement light S IN onto the irradiation region 10. The irradiation region 10 is defined at the passage location of the product P, that is, the passage location of the recess 410. The irradiation optical system 230 can be composed of a transmission optical system such as a lens, a reflection optical system such as a mirror, or a combination thereof. As the recess 410 moves, the irradiation region 10 will be traversed sequentially by a plurality of products P.

[0080] The light source 210 repeatedly generates pulsed light at a predetermined frequency (period). The operating frequency of the light source 210 may be determined according to the moving speed of the recess 410, that is, the transfer speed of the product P, and is determined such that a plurality of measurement lights S IN are irradiated onto the same product P while one product P exists in the irradiation region 10.

[0081] The operation of the light source 210 is independent of the operation of the transfer device 400, in other words, the position of the product P. Therefore, the measurement light S IN is repeatedly irradiated onto the irradiation region 10 even when the product P is not present in the recess 410.

[0082] The light receiving device 300 is provided above the recess 410. A through hole 412 is formed in the bottom surface of the recess 410. This through hole 412 is formed to guide the measurement light S from the irradiation optical system 230 IN to the bottom surface of the product P.

[0083] A pump 840 may be provided on the back side of the recess 410. The pump 840 constitutes a suction means. By making the back side of the recess 410 into a negative pressure, the product P will be attracted to the recess 410, and it is possible to prevent the product P from falling off from the recess 410 as the product P is transported.

[0084] The time waveform I OBJ (t) of the object light S is measured by the light receiving device 300. Also, a beam damper 820 is provided on the optical axis OA2 of the measurement light S OBJ to prevent stray light. IN The light receiving device 810 is provided to measure the spectrum of the measurement light S

[0085] The irradiation optical system 230 branches a part of the measurement light S IN as the reference light S IN to a separate arm by using a beam splitter or the like. The light receiving device 810 measures the time waveform I REF of the reference light S branched to the separate arm REF . This time waveform I REF (t) is equivalent to the time waveform I REF (t) of the measurement light S IN . IN (t)

[0086] The digitizer 830 includes an A / D converter, samples the outputs of the light receiving device 300 and the light receiving device 810, that is, the time waveforms I OBJ (t), I REF (t) at a predetermined sampling frequency, and converts them into waveform data D OBJ (t), D IN (t) of digital signals. When using the light receiving devices 300 and 810 with digital outputs, the digitizer 830 can be omitted.

[0087] The processing device 500 processes the digital waveform data D OBJ (t) and D IN (t), and obtains the transmission characteristic (or absorption characteristic) T(λ) of the product P. The processing device 500 can be implemented as a combination of a general-purpose or dedicated computer including a storage medium such as a processor, a memory, and a hard disk, and a software program. The processing of the processing device 500 is as described above.

[0088] According to this inspection device 800, for the product P, the measurement light S IN is irradiated from the conveyance device 400 side, so that the object light S OBJ can be prevented from being blocked by the through hole 412, and more object light S OBJ can be detected by the light receiving device 300.

[0089] In the inspection device 800 of FIG. 13, when the product P does not exist in the recess 410, the measurement light S IN passes through the through hole 412 and leaks to the light receiving device 300 side. Assuming that the light receiving device 300 is arranged on the optical axis OA2 of the measurement light S IN , when the product P does not exist on the optical axis OA2, the high-intensity measurement light S IN directly enters the photosensor 302, which is not preferable. Therefore, the light receiving device 300 may be configured such that the measurement light S IN does not enter the photosensor 302 when the product P does not exist in the recess 410.

[0090] For example, the light receiving device 300 is configured such that a component S OBJ of the diffused transmitted light (object light S IN ) of the object OBJ, which is radiated in a direction deviated from the optical axis OA2 of the measurement light S θ (the deviation angle is θ), enters the photosensor 302.

[0091] In addition, the object light S OBJIt does not have to be incident on the optical sensor 302 and may be incident on the incident aperture of the light receiving device 300.

[0092] Thereby, when the product P does not exist in the recess 410, the light receiving device 300 can be protected. At this time, the light source 210 of the lighting device 200 can be made to free-run asynchronously with the operation of the transport device 400, and shutter control synchronized with the operation of the transport device 400 is also unnecessary.

[0093] The embodiments merely show the principles and applications of the present invention, and many modifications and arrangement changes are recognized in the embodiments without departing from the idea of the present invention defined in the claims.

Explanation of Reference Numerals

[0094] OA2, OA3 Optical axes 10 Irradiation area OBJ Object 100 Optical measurement device 200 Lighting device 210 Light source 220 Pulse stretcher 230 Irradiation optical system 300 Light receiving device 302 Optical sensor 310 Condensing optical system 312 Lens 400 Transport device 401 Support portion 402 Aperture 410 Recess 412 Through hole 500 Processing device 800 Inspection device S IN Measurement light S OBJ Object light 810 Light receiving device 820 Beam damper 830 Digitizer 840 Pump P Product

Claims

1. A transport device for supporting and transporting an object, comprising a transport device that supports the object at its support portion, an illumination device that irradiates a first surface of the object with measurement light that is coherent light whose wavelength changes over time, via the support portion, a light receiving device that detects diffused transmitted light radiated from a second surface of the object, and comprising the support portion is provided with an opening narrower than the object, the illumination device irradiates the first surface of the object with the measurement light through the opening of the support portion, the inside of the transport device is maintained at a negative pressure, the opening serves as an air inlet, and the object is sucked to the opening, characterized in that it is an optical measurement device.

2. The transport device has a plurality of the support portions each of which supports an object, the plurality of support portions each include a recess provided on a common surface of the transport device, and the opening is a through hole formed in a bottom surface of the recess, characterized in that it is the optical measurement device according to Claim 1.

3. The illumination device includes a light source head that generates the measurement light, and a folding mirror provided inside the transport device, and comprising the transport device has a window for introducing the measurement light from the light source head into the inside of the transport device, the folding mirror reflects the measurement light incident through the window toward the first surface of the object, characterized in that it is the optical measurement device according to Claim 1 or 2.

4. The light receiving device includes an optical sensor smaller in size than the object, and a condensing optical system including a lens larger in size than the object, and characterized in that it is the optical measurement device according to any one of Claims 1 to 3.

5. The light receiving device includes a photosensor, and is configured such that a component of the diffused transmitted light of the object that is radiated in a direction deviated from the optical axis of the measurement light enters the photosensor. The optical measurement device according to any one of claims 1 to 3.

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